According to a Conference Board of Canada’s report released Wednesday, the development of the country’s oil sands deposits is one of the largest development projects in the nation’s history.

“It is so large that it will rival massive public works projects in scale, such as the building of the Interstate Highway System in the United States,” says the report.

But CBC News, which obtained the April memo from a high-ranking official within Canada's Department of Natural Resources, is reporting that investors may find future returns not as spectacular as promised.